Exposure meter for photographic or cinematographic purposes



H. BROSCHKE Sept. 26, 1961 EXPOSURE METER FOR PHOTOGRAPHIC OR CINEMATOGRAPHIC PURPOSES Filed July 16, 1958 5 Sheets-Sheet l /5a 59a 5.9 50 505 5/ 56 54 53 57a 52 52a Sept- 26, 1961 H. BROSCHKE 3,001,460

EXPOSURE METER FOR PHOTOGRAPHIC OR CINEMATOGRAPHIC PURPOSES Filed July lb, 1958 5 Sheets-Sheet 2 "5 Fig. 5

INVENTOR. ma M H. BROSCHKE sept. 26, 1961 EXPOSURE METER FOR PHOTOGRAPHIC OR CINEMATOGRAPHIC PURPOSES 5 Sheets-Sheet 3 Filed July Lb, 1958 73h 73a 7/a 60b INVENTOR.

Sept. 26, 1961 H. BROSCHKE 3,001,460

EXPOSURE METER FOR PHOTOGRAPHIC OR CINEMATOGRAPHIC PURPOSES .59a /5a 606 5/ 80a :90 /a 82 54 83 6.5

INVENTQR.

Sept. 26, 1961 H. BRoscHKE 3,001,460

EXPOSURE METER FOR PHOTOGRAPHIC OR CINEMATOGRAPHIC PURPOSES Filed July 16, 1958 5 Sheets-Sheet 5 mi@ f5 Patented Sept.,A 26, i951 s mn 4to*- nxrosonn imma noir rr-roroonxrnrc on" cnana/rxroonarrnc ilunrosas-` Heinrich Broschlre, Wetzlartliahn), German-y,l assigner to This invention relates to a method and 5to an apparatus for ascertaining the correct yillumination or exposure measurement to be observed in taking photographic or cinematographic pictures by using an exposure measuring device which consists of a combination of an optical photometer and a photoelectric exposure meter;

Such combinations are per se. known inthe art. In such combinations it is known to ascertain the correct optical-photometric exposure value by a comparison between a small, sharply defined view-portion of the object and'a comparison surface and to measure the brightness of the comparison surface by a photoelectric exposure meter, the light value ascertained by said optical photometer being used as a computing factor for the light value ascertained by said photoelectric meter.

Inasmuch as the object to be photographed as a rule contains a very uneven division of dark and bright portions it may easily happen that the brightness of a very unimportant portion ofthe object may be compared with the comparison surface, so that a faulty exposure of important details of the object may occur. This may easily happen when the distance to the object is considerable and measuring near the object is impossible. The necessity of combining both light values by computing may cause `faulty results and prevent a direct coupling between the exposure measuring device and the exposure setting devices of a photographic or cinematographic camera.

The invention avoids such disadvantages and makes possible the direct coupling between such combined'measuring devices and the exposure setting means of a photographic or cinematographic camena.

Therefore, ran object of the invention is a method of measuring the illumination necessary for photographing an object by `the use of an optical comparison photometer together with a photoelectric exposure meter for photoelectric measuring the comparison brightness, which method consists in- First, determining the integral value of the brightness of a view-important portion of the object by said optical photometer, said portion of the object being of an optically predeterminated size;

Second, transferring said determinated integral brightness value as a correction value upon the follow up pointer of said photoelectrical exposure meter, the instrument pointer of which indicates the light value of the comparisonV brightness of the said optical photometer and Third, thereafter adjusting the exposure setting elements of the camera in accordance with the follow up position of the. said follow up pointer which has been corrected by the correction v-alue ascertained by the said optical photometer.

Al further object of the invention is to provide an exposure meter. device for determiningthe requisite illumination for the photographic taking of pictures according to the aforesaid method, comprising, in combination, an'optioal comparison photometer for determining the light valueorfa. view-important portion of the object to be photographed, a photoelectric exposure meter for photo electrically determining the comparison brightness of said optical photometer, a picture finder for' observing the'object' and showing fthe size of the object to be photographed, optical means in` saidpicture nder for viewing .the field of view of said optical comparison photometer in the path of Ythe finder bundle of light rays, optical means in said optical comparison photometer for producing a non-sharp image of predeterminated size of a view-important portion of the object in the field of view ofthe comparison photometer concentric withthe comparison light spot of the comparison photometer, lightweakening means in said comparison photometer, a scale connected to said light weakening means, means in said photoelectn'c exposure meter for stopping or loosening, respectively, the pointer of the photoelectric instrument in its stroke position in dependence upon the measuring operation of said optical comparison Photometer, a follow up pointer device in said photoelectrie meter adjustable with reference to the light values ascertained by said optical photometer and provided with means indicating the camera setting values, and means forilluminating evenly the comparison surface of Athe optical lcomparison surface ofthe optical comparison photometer and the photo cell of the photoelectric exposure meter.

Furthermore, objects 'of the invention are to provide coupling means for mechanically transferring the correotion value ascertained from the optical comparison photometer to the photoelectric exposure meter or its follow up pointer, respectively, and means for direct coupling between the scale means of the photoelectric exposure meter and the exposure setting means of a camera, including equalizing means to consider the non-linear characteristics of the pointer movement of the said photoelectric exposure meter.

The aforesaid and further objects of this invention will be more readily understood from the following specilication read in connection with the aompanying drawings, in which FIGS. 1-4 illustrate an optical-photoelectrical measuring device embodying the invention in which the viewing field of the photometer is mirrored in a picture finder, the viewing field of the latter shows the part of an object, which may be photographed by means of a photographic camera, not shown.

FIG. 5 shows the viewing lield of the finder with the viewing field of the photometer, according to the embodiment of FIGS. 14.-

FiG. 6 illustrates another embodiment of the invention like that of FIGS. 1-4 but with a part of the optical photometer directly arranged in the path of the light rays of the picture finder.

FIG. 7 shows the opticai-photoelectric device in an embodiment which includes a range finder.

FlGS. 8 and 9 illustrate arrangements in which light weakening means are included in the Ender.

FIGS. l0 and 1i illustrate an arrangement in which an adjustable gray wedge of the optical photometer is coupled with parts of the electric exposure meter.

FiGS. l2 and 13 illustrate a device embodying the invention in which the device is coupled with the camera exposure adjusting elements.

FIGS. 14 and l5 illustrate still another embodiment of t-he invention in which an adjustable gray wedge of the optical photometer is coupled with parts of the photoelectric exposure meter, the latter ybeing coupled with the camera exposure ladjusting means, and including mechanical equalizing means for considering the non-linear characteristics of the pointer movements of the photoelectric exposure meter.

The embodiment of the invention illustrated in FIGS. l5 comprises a housing 60 having a front Wall with `a light diiusing glass plate 1 and including an optical cornparison photometer as well 'as a photoelectric exposure meter and la view finder 4, S, the latter being combined with the optical photometert The photoelectric exposure meter comprises a photo cell 2 arranged behind the ditusing glass plate 1 and electrically connected with an instrument 50a, the pointer 50 of which is visible in a window 60b of the housing 60 opposite a leading scale 51. Additional scale means 52, 53 yand 54 are provided for cooperating with the leading scale 51 and the pointer 50, respectively, `as later on described.

The optical photometer comprises an opening 3 behind the diztusing glass plate 1 provided for the passage of the comparison rays of light of the optical photometer, towards a small comparison surface formed as a small mirror element 9b, which is arranged in an optical mixing element 9. By this arrangement, the comparison surface 9b of the optical photometer and the photo cell 2l of the photoelectric meter receive light from the same source, namely from the illuminated ditusng glass plate 1.

Furthermore, the optical photometer comprises a tube 10a with an opening 1G in the diffusing glass plate 1 through which enters Ia bundle of light rays 7 coming from the object the exposure value of which has to be measured. The incoming light rays 7 `are reflected by .an inclined mirror 8 to the surface 9a of the optical mixing element 9, the surface 9a being matted and serving as a ground glass, the free area of the matted surface 9a being defined by a diaphragm 11.

The angie of the bundle of rays which enters through the opening 10 is dimensioned to be an integral division of the entrance angle of the iinder 4, l5. The opening 10 and the opening in the diaphragm 11 may be dimensioned to suit the use of `objectives with different focus and these openings may be adjusted or made interchangeable. These and other `detailsl are not illustrated.

The optical proportions of the iinder 4, are so selected that 'the iinder may be usable for a photographic or cinematographic camera. If camera objectives with different focus are used, the picture field appearing in the iinder may be made adjustable or coupled to a corresponding adjusting means for limiting the measuring eld.

The finder 4, 5 is provided with `an inclined mirror 6, arranged between the Ifinder lenses to receive light rays coming from the mirror element 9b and from the matted surface 9a and to reflect these light rays towards the ocular lens 5 of the finder. Between the optical mixing element 9 and lthe mirror 6 there is arranged a lens 12, which serves together with the finder lens 5 to observe the mirror 9b and the matted surface 9a.

The size of the mirror 9b and the size of the free area of lthe matted surface 9a are so selected that, visible in the viewing field B of the finder 4, 5, the adjustable iield of comparison which corresponds to the size of the mirror 9b is seen as a small field M in the middle of a much larger field O corresponding in size to the opening in the diaphragm 11, the iield O, however, is small in comparison with the viewing field B of the iinder 4, 5, as shown in FIG. 5 and marked in FIGS. l and 5 by the langles O', B.

In order to assimilate the brightness of the comparison field M with the brightness of the non-sharp object tield O a rotatable gray wedge 15, FIGS. l and 3, may be used. The gray wedge may rotate about the axis of the tube a and extends between the opening 3 and the mirror element 9b or optical mixing element 9, respectively. By turning an operating wheel 15a, FIGS. 3 and 4, operatively connected with the gray wedge 15 by gear means 15e, the brightness of the comparison field M or the light entering the mirror element 9b, respectively, may be weakened or strengthened. The gray wedge 15 is connected with a scale 15b, FIGS. l and 4, which is readable by optical means 15e, 15jc in a Window 60a of the housing 60. The scale 15b indicates steps of brightness.

The arrangement may include means within the range of the diffusing glass plate 1 whereby the light which is directed both to the photo cell 2 and to the comparison photometer is limited. For example, as seen in FIG. 2, such limiting means may consist of louvres 13 and a lens 4 14 may be placed in `axial yalinernent with the opening 3.

Relating to the photoelectric exposure meter being part of the exposure measuring device, the two scale disks 53 and 54 are frictionally connected and co-axially mounted as shown in FIGS. 3 and 4. The scale disk 53, nearest the fixed scale disk 52, bears a scale indicating time values of exposure. The other scale disk 54 bears a scale indieating values of brightness and Ithese latter values correspond to the steps or Values of brightness of the scale '15b of the gray wedge 15 which are visible within the window 60a.

The markings of optically-photometrically measured brightness values on the scale disk 54 serve as follow up pointer for the pointer 50 of the photoelectric meter 50a. The corrected relations between the photographic exposure values are readable in time and diaphragm values on the disks 52 and 53, when that brightness value on the scale disk 54 which corresponds with the optically-photometrically measured brightness value readable in the window 60a has been brought in coincidence with that posi- 4tion of the pointer 50 which has been obtained as a value considering the brightness of the diffusing glass plate 1 during the optical-photometrical measuring of the object brightness. The scale disks 53 and 54 are provided for the consideration of exemption constants such as ilm sensitivity, ilters rand the like land may be relatively adjustable. rThe adjusting may be controlled by markings 55 on the scale disks 53 and 54 and the adjusted value may be read in numbers appearing in the Window 52a of the fixed scale disk 52.

Inasmuch as this embodiment of the invention requires that the photo-electrically measured brightness values marked by the strokes of the pointer 50 be corrected by means of the optically-photometrically observed value of the brightness of the object, it is necessary that the instrument pointer S0, visible within the window 60b, be stopped in its stroke position, which it has reached when the instrument is in light measuring position.

This is accomplished by means of two clamping members 56 and 57, FIG. 3. The clamp 56 is xed. The clamp 57 is formed on the free end of a pivoted lever 57a. Another lever 59 engages the short end of the lever 57a as shown and carries a iinger member 59a. The latter lies within the range of the wheel 15a which serves to yadjust the gray wedge 15. A spring 58 acts upon the lever 59 to clamp the pointer 50 between the clamping members l56, 57. Before it is possible to operate the wheel 15a for adjusting the gray wedge 15, the linger member 59a has to be pressed down against the yforce of the spring 58, thereby releasing the pointer 50 `from the clamps 56, 57. When the wheel 15a is released, the spring 58 :again acts to yclamp the pointer 50 in whatever extreme stroke position it has reached.

This exposure measuring device embodying the invention as above described is formed as a pocket instrument. It may be used as a separate instrument or releasably mounted on a camera housing of any type. Its operation and its handling is as follows:

The iinder 4, 5 is `directed on the object and then there appears in the rinder picture field B, FIG. 5, a relatively small bright spot M which is an image of the mirror 9b which is illuminated through the opening 3 and which serves as a comparison surface. Around this comparison spot M appears also a non-sharp picture O of a portion of the object. The size of O is determined by the size of the opening 10` and the size of the ground glass 9a. The non-sharp appearance of O is caused by the direct imaging of a limited portion of the object by the light rays coming in through 'the opening 10 and reilected upon the matted plate 9a of the optical mixing element 9, FIG. l.

The spot M and the surrounding portion O are directed by the iinder 4, 5 upon that portion of the object which has to be correctly exposed in the final picture. The matted plate 9a causes a ditiuse distribution of the brightness of that portion of the object (integral brightness) which is under consideration and which brightness is thereafter photometrically compared with the brightness of the spot M.

'Ilhe gray wedge I5 is then rotated by operation of the Wheel 15a until the brightness of M and O are even.

Thus the gray wedge reaches an end position in which it f indicates a comparison value of the brightnesses between the brightness of the important portion O off the object to be photographed and the brightness of the diiusing glass plate 1, and which is then used to correct the photoelectrically measured brightness value of said :glass plate 1.

During the optical-photometrical determining of the comparison value the pointer t? of the photoelectrical meter 50a moves freely because ,the users inger operating the Wheel a depresses the nger member 59a and thereby holds open the clamps 56, 57.- Thereby, the pointer 50 moves into a position which corresponds to the brightness of the diiiusing glass plate l. After determining the comparison value the users iingerlets go of the wheel 15a and the finger 'member 59a, whereby the spring 5S acts to clamp the pointer 50 in its stroke position, the pointer 5t? then being held stationary in that position by the clamps 56, 57.

rThe brightness value, -for example 2, FIG. 4, appearing in the window 60a, and which is obtained by the adjustment of the gray wedge 15, is then, by using the corresponding number 2 on the rotatable scale disk 54 as a follow up pointer brought in coincidence with the pointer 5t) 'of the instrument 50a, the pointer 50 being held stationary in its stroke position by the clamps 56,v 57.` The scale disk 53 frictionally connected with the scale disk 54 follows the follow up movement of the latter.

r[he fixed scale disk 5?. shows the camera diaphragm opening values and the `corresponding exposure time values may then be read upon the scale disk 53 `and thereafter be transferred to the camera exposure adjusting elements.

FIG. 6 shows another embodiment of the invention in AWhich that part of the optical means by which the non-sharp object View O is obtained `and the mirror element forming the comparison spot in the diaphragm 11 arearranged immediately between the tinder lenses 4, 5. The photo cell 2 and the ent-rance opening 3 for cornparison light of the optical photometer are arranged behind the light diiusing plate l. The bundle of light rays which comes from the opening 3 and serves for comparison is reflected into the iinder path of light rays by the mirrors 2b and 2i, the latter beingV part of the optical mixing element 24; The size of the mirror 21 determines thesize of the comparison light spot M. rEhe finder is provided with a tube 23 having a front opening- 22 and a rear opening which is covered with the matted glass surface 24a of the optical mixing/element 24. The. non-sharp picture of the object appears on the matted glass surface 24a. The arrangement also includes a lens. 25. which together with the nder lens 5 forms a magnifyingglass for observing the comparison bright spot M' within the surrounding iield O, FIG. 5. Between the reflecting mirror and the comparison surface in the opening 3 there is again arranged a rotatingor slidably operated gray wedge 15 which serves the purpose of assimilating the brightness of the spot M within the brightness of the field O. The arrangement in FIG. 6 is otherwise like that shown in FIG. 5 and is operated in the same manner.

FIG. 7 illustrates another embodiment of the invention in which the entire exposure measuring device is combined with an existing range finder. In this embodiment the exposure measuring device is formed to iit an existing range finder, which may be a pocket instrument or which may be built into a camera housing. The opticalelectrical measuring elements of theexposure meter are inL this embodiment formed as a unitary structure arranged- :1;

to be placed in front of the range finder.V

'Ihe exposure meter includes the diiusing glass'plate 1 with the photo cell 2, the comparison surface in the opening 3, the gray wedge l5, the optical mixing'element 9 with the mirror opening 9c `and the mat surface glass disk 9a with a limiting diaphragm '11, the opening 10 for the bundle of light rays coming from the selected `portion.l

of -t-he object and the reflecting mirror 8.

The mirror opening 9c serves the same purpose as the.v mirror spot 9b, 21, in FIGS. 1-6 and determines thesize of the comparison bright spot M. The instrument- 50a with its pointer 50`is not shown but may be like that shown in FIGS.y 1-4.

In order to adapt this exposure meter to the opticalA properties of a range nder or a measuring finder there is provided yet another optical element in the form of a4 lens 36. The latter is for the purpose of enabling theuser to utilize the exposure meter in front of the measuring rays entrance opening 37 of a range nder of usualv construction.

Such a range finder of known construction consists lforv example of a lnder 4, 5 with a reecting mirror 34, alens 3S in the path of the deliected light rays, the lens 35.'- together with the ocular lens 5 of the finder 4, 5 Vforming a magnifying glass for observing an intermediate pictureA plane 31 within view limiting marks 31a. Further, such a known instrument includes `an adjustable objective 32 for deecting the measuring picture in the intermediate picture plane, also the ybase end mirror 33 and thev light guiding mirrors 36, 36a. "Ille base and mirrors 33 and 34 and the mirrors 36 and 36a form an image erecting-sys tern in order to erect lthe image caused by the real imaging objective 32.

When the parts are assembled as shown in FIG. 7 the:

non-sharp iield O and the comparison field M of the optical photometer will be seen in the finder 4, 5 instead of this arrangement, one may use a reversible mirror or'.4 prism arrangement which either releases the opening 37 in order to measure the range or leads the united bundle or" light rays of the optical photometer arrangement into t the opening 37 of the range iinder.

The photoelectrical exposure meter arrangement of the above stated embodiment may be the same as shown in.

FIGS. 1 4. Also operation and handling of the optical.- photometrical as well as of the photo-electrical exposur meter device is the same as stated above.

These above described arrangements provide a nonsharp object field O `for optically-photometrically measuring purposes which eld is seen in the finder field B surrounding the centrally disposed bright spot M.

Diiculties in the light measuring operation may however occur when the contrast in light illumination is too strong for correctly -measuring the diierences between O and M. This may occur when the brightness of the field B outshines the brightness of the eld O and of the spot M.

In such cases one may use an adjustable polarizer 40,. FIG. 8, in the iinder opening and an analyzer- 42 combined with the mirror 4i the latter reecting the rays coming from the optical photometer into the nder. By

adjusting the polarizer, the brightness of the object iield` B seen in the finder may be varied to suit.

FIG. 9 illustrates another form of light weakening means provided in the iinder to vary the brightness of the The mirror 45, which.- reiiects the photometric fields of View O and M inthe., path of the finder light rays is made slidable or rotatable.. and formed as a gray wedge in that the mirror 45 iis pror object field B seen in the iinder.

vided with a stepwise or continually varying transparency. This arrangement possesses the advantage that if the brightness of the finder eld B is weakened, the brightness of the comparison lields O and M is increased. If the transparency of the mirror 45 is of continually varying character then it is advantageous tc use adjustable gray wedges 46, 47 near the optical mixing element 9. The wedges serve the purpose of compensating for the uneven reflection of the lields O and M, caused by continually varying transparency. The wedges 46, 47 are adjusted when the apparatus is built and require no after adjustment.

The foregoing described embodiments of the invention relate to exposure meter devices in which the opticalphotometrically measured brightness value is combined with the photoelectrically measured brightness value under the control of the vision of the photographer. However, in these arrangements it is possible to couple the gray wedge adjusting means of the optical photometer with the follow up pointer of the photoelectric exposure meter as well as the follow up pointer of the electric exposure meter to the corresponding exposure adjusting elements in a photographic camera or cinemaphotographic camera. The tirst mentioned coupling transfer is done by simple gear means the second means of a differential mechanism having means for adjusting the time and diaphragm adjusting elements of the camera.

FIGS. 10-15 illustrate schematically mechanisms in which the means for adjusting the gray wedge is coupled with the electric exposure meter in such a manner that the value of brightness ascertained with the optical photometer device is automatically transferred to the photoelectric exposure meter mechanism. The value scale of brightness b, FIG. 1, of the gray wedge 15 may then be dispensed with.

FIGS. 12/-15 illustrate schematically mechanisms in which the follow up pointed means of the photoelectric exposure meter is coupled with the exposure adjusting means of a camera. Only the coupling means are shown and described. The optical and photoelectrical means of the exposure measuring device as well as its operating and handling for measuring purpose may be the same as shown and described in the foregoing embodiments.

FIGS. 10 and 1l illustrate an embodiment of the invention in which the means for adjusting the gray wedge 15 is coupled with the photoelectric exposure meter. The gray wedge is adjustable into different positions by operation of the wheel 15a. The gear means 15e of the gray wedge 15 meshes with the teeth 70a of another gear 70. The latter is fast on a shaft 7Gb which also carries an uppermost or forefront scale disk 71 having two windows 71a and 71b. The scale disk 71 is a scale disk of the photoelectric exposure meter, see FIG. 3, and may carry a camera diaphragm opening scale 71d.

Behind the scale disk 71 there is arranged a second rotatable scale disk 72 which is frictionally connected with a third scale disk 73. The scale disk 72 carries scales of time values `and brightness or light values which are read in the windows 71a and 71b of the disk 71. 'I'he arrangement is such that the scale of time values are seen opposite the diaphragm values on the scale disk 71.

The scale disk 72 also carries a lilm sensibility-degrees scale which is visible in the window 73a of the scale disk 73. The sensibility-degree scale is readable in relation to the mark 73b on the disk 73. The scale disk 73 carries a mark 73C Awhich serves as a follow up pointer which is movable by means of the leading scale 51 into alinement with the instrument pointer 50. The pointer 50 is visible in the window tlb of the housing 60.

When the follow up pointer 73e has been set with reference to the instrument pointer S0, the time values on the scale disk 72 corresponding to the diaphragm values on the scale disk 71 can be read with reference to the corresponding diaphragm values 71d. The light values visible in the window 71b may be read also by means 8. of a `further mark 711e on the scale disk 71. The optical-photometrieal and the photoelectrical means as well as the operation of this arrangement is otherwise like that described in connection with FIGS. l-9.

Inasmuch as the adjusting means of the gray wedge is coupled with the diaphragm scale 71 of the photoelectric exposure meter, the operation of the optical-photometric mechanism causes automatically the corresponding adjustment of the scale disk 71 which shows the diaphragm values 71d. The time values on the scale disk 72 will be alined with the corresponding diaphragm values 71d on the scale disk 71 by moving the mark 73C into alinement with the instrument pointer 50.

FIGS. l2 and 13 illustrate an embodiment of the invention-built into a photographic camera-in which the adjustment of the gray wedge y15 is mechanically transferred onto the photoelectric meter 50a and the follow up pointer means of the photoelectric meter 50a is coupled with the exposure adjustment means of a camera. Otherwise, the optical-photometrical and the photoelectrical means for measuring and its operation are the same as described in FIGS. 1-9.

The rotary adjustment of the gray wedge 15 of the optical photometer causes a rotary adjustment of the photoelectric meter 50a including the leading scale 51. This embodiment provides a scale disk with a follow up pointer 80a mounted coaxial with the measuring mechanism and operating in conjunction with the leading scale 51. The scale disk 80 is frictionally connected with a lm-sensibility-scale disk S1 and adjusted with reference to the scale disk 81 by means of a pointer mark 80h. The sensibility-scale disk 81 has a gear 81a which meshes with another gear 82. The latter gear 82 is part of a differential mechanism 83-36. The differential mechanism transfers the adjusting movement of the follow up pointer 80a to the element 87 for adjusting the camera diaphragm or to the element 88 for adjusting the time setting mechanism of a camera, one of the exposure adjusting elements being predetermined and preset in considering the most important exposure factor for obtaining tthe desired view.

The transfer of the optically-photometrically measured values to the electrical exposure meter is as follows. The rotary adjustment of the optical gray wedge 15 is caused by operation of the knob 15a as above described. Simultaneously therewith and by means of the meshing gears 15e and 70 the photoelectric meter 50a including the pointer 50 and the leading scale 51 is adjusted.

The window 60b in the housing 60 is so placed that the leading scale 51 of the photoelectric exposure meter together with the entire range of the stroke of the pointer 50 remain visible as a unitary adjustment range of the photoelectric meter 50a.

The pointer 50 of the photoelectric exposure meter is again arrested in its end-stroke position after the finish of the optical-photometric measuring movement. The correct posit-ions of the camera diaphragm and the camera time setting elements are then obtained by alining the follow up pointer 80a with the pointer 50, the follow up movement is transferred on the non-preset exposure adjusting element of the camera.

'Ihe numerical scales for visibly indicating the single measuring results are no longer required in the exposure measuring device, but may of course be consulted on the exposure adjusting elements of the camera to check the results of the operation.

The embodiment illustrated in FIGS. 14 and 15 refers also to a measuring device built into a camera. It also includes -a coupling arrangement between the rotary adjustment of the gray wedge 15 and the rotatable photoelectric meter 50a. The latter, in this arrangement, includes a cam disk 90 which rotates with the rotary movement of the photoelectric meter 50a. A follow up pointer 91, which cooperates with the instrument pointer 50, is formed at the free end of a lever 91a which is aoonaeo nected with a gear 94. The latter meshes with anotherv gear 9S.' The gear 95 corresponds to the gear 82.ofthe embodiment'accordingto FIGS. `12k and 13 and forms.

connection with the `differential mechanism .8S-86 for adjusting the adjusting elements in the camera in the.r

same manner as described .in connection with the embodiment illustrated in FGS. l2 and 13. The lever 91a. is formed 1with a cam'nose 91C which lis held on the cam 90 by a spring 9l1b.

To consider additional photographic factors such as sensitivity of the lm, filters or the like relative adjustment between.. the frictionally connected disk. 93 and gear .-94 is provided by a relative movement between'the adjustable scale 93a on the turntable 93and a pointer 94h onthe `gear 94,' the scale`93a being visible in the window 94a.

Inv this -embodiment the cam controlled movementof the follow up pointer 91 is provided for the purpose of exercising the equalization function of the leading scale 51 and whereby the latter is no longer required. The measuring and adjusting operation of this embodiment is similar to that `described in connection with FIGS. 12 and 13.

I claim:

1. A photographic exposure meter device for determining lthe requisite illumination for the photographic taking of pictures comprising, in combination, an optical comparison photometer for determining the light value of the object to be photographed, a photoelectric exposure meter for photoelectrically determining the arnbient brightness, a picture inder for observing the object to be photographed, optical means in said picture finder for viewing the eld of view of said optical comparison photometer in the path of the iinder bundle of light rays, optical means in said optical comparison photometer for producing a non-sharp image of predetermined size of a portion of the object in the eld of view of the comparison photometer concentric with the comparison light spot of the comparison photometer, light weakening means in said comparison photometer, means in said photoelectric exposure meter for holding and releasing the pointer of the photoelectric instrument in its indicating position in response to the measuring operation of said optical comparison photometer, and means for illuminating uniformly the comparison surface of the comparison photometer and the photo cell of the photoelectrical exposure meter.

2. A photographic exposure meter device as dened in claim 1 said optical means in said optical comparison photometer, for producing a non-sharp image comprising a mat surface for creating a non-sharp part-picture and an illuminated mirror element in the measuring eld serving as a comparison surface which is smaller than the surrounding not-sharp object field and the latter smaller than the surrounding held of view of the finder each of them lby a multiple of the sizes thereof.

3. A photographic exposure meter device as defined in claim 1 said optical means in said picture finder including means for optically combining the light paths of the comparison light rays with the picture finder light rays, and further including an optical mixing element with a mat surface and a small mirror element both included in the path of the picture finder light rays.

4. A photographic exposure meter device as defined in claim l including light weakening means in the path of the said picture finder bundle of light rays.

5. A photographic exposure meter device as defined in claim 1 said optical means in said picture iinder including path of the bundle of light rays in the picture nder.

6. A photographic exposure meter device as defined in claim l said optical means in said picture nder including a transparent mirror of continually variable transparency in the path of the finder light rays for optically combining therewith the rays in thetield of view ofthe com parison photometer and including compensation lighty weakening means positioned in the path of the light rays of said comparison photometer.

7. A photographic exposure meter device as dened in claim l said last mentioned means including a lighting.

did-using glass plate for illuminating the comparison surface of the optical photometer and the photo cell of the photoelectricalexposure meter to thesame extent.

8. A photographic exposure device as deiined in claim 1 said means for holding and releasing the pointer of the photoelectric instrument including clamping means for the photoelectric instrument pointer toclamp-the instrument pointer when not operating said light weaken# ing means of said optical photoemeter.

9. A photographic exposure meter device as dened in olaim'l further'comprising scale means and coupling means between said light weakening means of said optical photometer and the scale means.

l0. A photographic expostu'e device comprising in combination, a photographic camera picture iinder; a photographic camera range finder having a measuring opening; a unitary structure of an optical comparison photometer for determining the light value of 1the object to be photographed, a photoelectric exposure meter for photoelectrically determining the ambient brightness, optical means in said photometer for producing a nonsharp image of pre-determined size of a portion of the object of a eld of the View of the comparison photometer concentric with the comparison-light spot of the comparison photometer, light weakening means in said comparison photometer, means in said photoelectric exposure meter for holding "and releasing the pointer of the photoelectric instrument in its indicating position in response to the measuring operation of said optical comparison photometer, and means for illuminating nniformly the comparison surface of the comparison photometer and the photocell of the photoelectric exposure meter; said unitary structure being mounted in front of the measuring opening of the said range inder; yand optical means for adapting said unitary structure to the optical means in said picture linder and said camera range nder.

11. A photographic device including a photographic exposure meter and diaphragm exposure adjustment means for a camera, comprising, in combination an optical comparison photometer for determining the light value of the object to be photographed; a photoelectric exposure meter for photoelectrically determining the ambient brightness; a picture finder for observing the object to be photographed; optical means in said picture finder for viewing the held of view of said optical comparison photometer in the path of the inder bundle of light rays; optical means in said optical comparison photometer for producing a non-sharp image of predetermined size of a portion of the object in the field of View of the comparison photometer concentric with the comparison light spot of the comparison photometer; adjustable light .weakening means in said comparison photometer; coupling means between said light weakening means and said photoelectric meter; scale means for use as a follow-up pointer of said photoelectric meter; coupling means for operatively connecting said scale means and one of said diaphragm and exposure adjusting means; means in said photoelectric meter for holding and releasing said pointer in its indicating position in response to the measuring operation of said optical comparison photometer; and means for illuminating uniformly the comparison surface of the comparison photometer and the photocell of the photoelectric cell of the exposure meter.

12. A photographic device including a photographic exposure meter and diaphragm and exposure adjustment means for a camera, comprising, in combination an optical comparison photometer for determining the light value of the object to be photographed; a photoelectric exposure meter for photoelectrically determining the ambient brightness; a picture nderfor observing the object to be photographed; optical means in said picture finder for viewing the field of View of said optical comparison pliotometer in the path of the nder bundle of light rays; optical means in said optical comparison Photometer for producing a non-sharp image of predetermined size of a portion of the object in the eld of view of the comparison photometer concentric with the cornparison light spot of the comparison photometer; adjustable weakening means in said comparison photometer; coupling means between said light weakening means and said photoelectric meter; scale means for use as a follow-up pointer of said electric meter; diiferential coupling means for operatively connecting said scale means and one of said diaphragm and exposure adjusting means; means in said photoelectric meter for holding and releasing said pointer in its indicating position in response to the measuring operation of said optical comparison Photometer, and means for illuminating uniformly the I12 comparison surface of the comparison photometer and the photocell of the photoelectric cell of the exposure meter.

13. A photographic exposure meter device as defined in claim 12 the photoelectric meter of which is rotatable and is coupled with the -adjustable compensating light weakening means of said optical photometer, said photoelectric meter comprising cam means coacting with the follow up pointer for compensation of the non linear 10 characteristic of the movement of the instrument pointer.

References Cited in the file of this patent UNITED STATES PATENTS 15 2,143,500 Smethurst et al. Jan. 10, 1939 2,183,217 Goldsmith Dec. l2, 1939 2,478,406 Lamb Aug. 9, 1949 FOREIGN PATENTS 757,898 France Oct. 16, 1933 

